Venting The Product; Manual Operation; Automatic Operation With Float Switch; Pumping To Low Water Level - Grundfos Unilift CC 5 Installation And Operating Instructions Manual

3.1 Venting the product

The pump is self-venting. A vent valve is built into
the lifting handle. The valve allows air to escape from
the pump in case the free air flow through the outlet
pipe is blocked. Once the pump is vented, the valve
normally closes.
If the pump sucks air or water with a high air content,
the valve may leak a mixture of air and water. This is
no fault but a natural consequence of the opening
and closing of the valve.
Fig. 12 Vent valve

3.2 Manual operation

Start and stop the pump via an external switch.
To eliminate the risk of dry running, check the water
level regularly during operation. This can for instance
be done by means of an external level controller.
In order for the pump to be able to self-prime when
started, the water level must be at least 25 mm.
When the pump sucks water, it can pump down to 20
mm water level.

3.3 Automatic operation with float switch

During automatic operation, the pump will start and
stop, depending on the water level and the float
switch position and cable length.
3.3.1 Forced operation of pump with float switch
If the pump is used to drain water below the stop
level of the float switch, the float switch can be kept
in a higher position by fixing it to the outlet pipe.
During forced operation, the water level must be
checked regularly to prevent dry running.

3.4 Pumping to low water level

The pump can pump down to 3 mm when the inlet
strainer is removed.
These conditions must be fulfilled:
• The inlet strainer must be removed.
• The pump must be placed on an even, horizontal
surface.
• The water must not contain particles which may
block the pump inlet.
• The water level must be minimum 5 mm when the
pump is started.
Fig. 13 Low water level
Removing the inlet strainer
To remove the inlet strainer, insert a screwdriver
between the pump sleeve and the inlet strainer and
turn it.
Fig. 14 Removal of inlet strainer

3.5 Thermal protection

If the pump is running without water, or if it is
otherwise overloaded, the built-in thermal switch will
cut out.
When the motor has cooled to normal temperature, it
will restart automatically.
7